Hydropneumatic accumulator



NOV. 28, 1933. HOLVECK 1,937,149

HYDROPNEUMATIC ACCUMULATOR Filed June 20, 1931 Patented Nov. 28, 1933TUNITED STATES,

This invention relates to hydro-pneumatic accumulators such as areemployed with hydraulic 7 pumps, and also to a method of establishingthe desired pneumatic pressure within such anaccumulator. 1.

An object of the invention is-to produce an improved hydro-pneumaticaccumulator.

A further object is to produce an improved method of charging such anaccumulator with the desired degree of pneumatic pressure.

These and other objects which will be made more apparent throughout thefurther description of the invention, are attained by means of theapparatus herein illustrated and described.

In the drawing Figure 1 is a diagrammatic view of a hydraulic pumpassociated with a two-compartment hydro-pneumatic accumulator embodyingmy invention; and Fig. 2 is a fragmental sectional view illustrating,more or less diagrammaticaly, a detail of construction of the tank shownin Fig. 1. Y

The accumulator illustratedc'onsi'sts'essentially of a two-partaccumulator so arranged that both parts maybe employed as a singlecompartment accumulator, or so that-onepart may be employed inconnection with a hydraulic pump in charging the other pressure. v vHydro-pneumatic accumulatorsordinarily consist of an airtight tankenclosing a single compartment andhaving a liquid inlet port at thelower endthereof, which isconnected to a source of liquid underpressure,such as a hydraulic pump,'and also to a delivery or distribution systemfor such liquid. The accumulator receives and stores what may be termeda reserve supply of liquid and the arrangement is ordinarily such thatair 'is trapped within the-upper portion of the tank and, by beingcompressed, exerts pres- 40 sure on the liquid within the tank andthereby establishes what may be termed an artificial or a pneumatic headfor the'liquid; 3 Accumulators,

such as described, are included as a, partof a liquid-distributionsystem, where it is desired to with the desired pneumatic sure;A'separate-air compressor is ordinarily employed for initially, andthereafter periodically "charging the accumulator with compressed air soas'to maintain the desired quantity of compressed air and the desiredvolume of liquid stored within the accumulator. Such compressors,although adding materiallyto'the' cost of an' accumulator installation;are of relatively low capacity and cmnsequently considerable time isexpended'in charging the accumulator with pneumaintain the liquid in thesystem under high pres? matic pressure, hereinafter termed compressedair or air pressure.

Under normal operating conditions it is usuau necessary to periodicallyrecharge the :accumulator with compressed air in orderto re-establish 3bthe desired proportionsbetween the quantity of compressed air and thequantity of liquid within the accumulator. 1 his recharging must be re-7 sortedto every several days, depending, of course, upon the conditionsencountered, but the function I of the air compressor, althoughimportant, is not such as to merit the additional expense ofa'highcapacity compressor. i

The arrangement of accumulator illustrated is such as to eliminate thenecessity of employing 7 a separate air compressor during the operationof initially charging the accumulator with compres sedair or.insubsequent. operations of reestablishing the :desired proportionjofair and liquid within-the accumulator. This is accom- I plished byemploying a two-p'artor two compartmentaccumulator in which the"arrangement is such that-one compartment may, efiect,

be employed as an air compressor for-charging the other compartment withcompressedair at a,

predetermined pressure and maylalso be employed' as the liquid supplychamber and a portion of' the airchamber of the accumulator when theaccumulator is used as ,a hydro-pneumatic accumulator.

As shown, the accumulator consists of a shell or tank 4, the interior,of which is divided into what may be termed a primary compartment .5

and a secondary compartment 6 by, an inter- ,7

mediate diaphragm or partition '7. The 'pri- '0 rnary compartment. isprovided at its lowerend with a liquid'inlet port 7', which communicatesthrough pipingB with the delivery mama ofthe, distribution 'systemQ Asshown, the piping}! is provided with a brancho'pipe 8, whichleadsto anatmospheric discharge and'is provided with a valve 8. Themain 9 receivesliquid, hereinafter termed Water, from a pump. 10. The pump may be ofany type, but as diagrammatically illus trated, is a multiple cylinder,single acting pum and is operatively connected to a driving motor 11.Water from any source is delivered tofthe suction port 12,0f thepump-and is .=delivered through the discharge L port [13 1 to thedelivery main 9.; As is usua1, a'ch'eck valve 14is interposed in themain 9 between the pumpi'and thedistribution system, but it preventsa'flow mule- I 1 L r-.114 f I q -4 to deliver waterv to the compartment5, the valve The water is then drained from the compartment 5 by openingthe valve 8 17 is retained closed.

During this draining operation the valve 'f-. is left open, since undersuch conditions, the drain- ,ing operation will be augmented by .theair'pressure delivered to the compartment 5 through the check valve 15'.It is, of course, apparentthat the check valve 16' is held closed by theincreased pressure of the air within the compartment 6. V

above described, exceptundersuch circumstances that the initialpressurev in the; compartment fi Afterthe drainingof the compartment 51's completed, the valve 8" is closed and airunder pressure frompipe 15is permitted 50.1111 that compartment. The valve 9' is retained in theclosed position. The pump 10 is then loaded or caused to deliver waterunder pressure to the compartment 5 with the result that theair in thatcompartment will be again displaced and forced into the compartment 6through the one way, or check valve 16. When thecompartment 5 iscompletely filled with liquid the pumping operationis stopped, the valve8" is opened and the procedure above described is continued untilthedesired air pressure is obtained within the compartment 6. I j

At the end of the operation just described it will be apparent thatthreevolumes of air, initially at 100 pounds pressure, have-been forcedinto the compartment 6, and that therefore the pressure in thatcompartment attheLendof the operation has been raised to 300'pounds.

At the end of the twelfth air displacing operation the pressure in thecompartment 6 will equal 1300 pounds per square inch. T In order toobtain the desired normal operating pressure within the combinedcompartments 5 and 6 I then operate the pump 10 to fill the compartment-5 to the normal water level,'suchas'indicatedin Fig. 1 by the dottedline X, it being understood that preceding this operation thecompartment 5 .was first filled with air at 100 pounds pressure. I thenclose the-valve 15." and by opening the valve 17 connect the twocompartments 5 and 6, and with the volumetric capacities of a tank such,'as illustrated, the resulting pressure within the accumulator willequal1000 pounds pressure. {It

is, of course, apparent that the predetermined pressure to which the airis raised .within' the compartment 6 will be, established bythevolumetric capacities of the.,twocompartments jarid the volumeof thecompartment 5 Which'is to be employed as a part of the combined airchamber.-

This is merely a matter of mathematical computation. a

After the accumulator is thus initially charged with air, the valve 9'is opened, the loading and unloading mechanism is rendered automaticand, in the example given, the pressure gauge 18 will record 1000 poundspressure and will therefore unload the pump; The pump 'will remain-un- Tloaded until delivery conditions, lower the level of the water withinthecompartment 6 to a level, such as indicated by the dotted line Y inFig. 1, at whichtime the pressure within the accumulator will havedropped a sufiicient amountto actuate the automatic mechanism to loadthe pump and to deliver water at the pumped pressure to the accumulator.

It will be apparent that to those skilled in the I art that the passage'17 and valve 17"may be. replaced by any means for establishingcommunication between the compartments 5 and 6 after the chargingoperation is completed. For example, the passage 17 and valve 17' may beomitted by providing means for opening the check valve level of theliquid to the top of the compartment 5, thus forcing the compressed airfrom compartment 5 into compartment fi. The valve 17f is then thedraining operation the valve 8 is closed andair at'l00 pounds pressurefills the compartment as the compartment 5, is lined with .water thepressure of the air. above the water is increased,

check valves 16 and-15' respectively, and the by so doing ,I mayprovidega more adequate pas sage between the two compartmentsthan wouldbe possible, or atleast otherwise, desirable.

. If, during normal operation, the quantity-of airin the accumulator isreducedthe recharging operation iscarried on inthe same manner as ismaterially abovethepressure available the air piping 15 A loss of airwill be noted byithe Water level within the icompartment 5 whenthe:pressure in the accumulator is raised to thenormal operating pressure1000 pounds) That I is to say, if the water level in the compartment-5-is 9' is closed and the-pump is operated. to raise the closed, thustrapping the highpressure air in compartment 6. The valve 15" and thevalve 8" arelthen opened to drain compartment 5. After 5. The pump isthen operatedto .again 'fill cornpartment 5 with water. It will. beapparent that and at some ater. levelthe pressure of the'air "in.compartment 5, vvvill exceed the "pressure .trapped within thecompartment Grand conse-. .q'uently air from compartment 5 will bedelivered through theone-wayvalve 16. to'the, compart ment 6 as theWater filling eperationis continued. [The rechargingjoperationjisthereafter similar to the charging operation andwhen' the desiredpressure is again obtainedwithinme compartment 6, the valves 8'1and.15'.5 closed,.th'e valves9 and '17 are openedand the .switch 21 ispermanently closed, with the result, that the 'appa'ratusis again incondition for nor- }mal operation and under' the automatic control ofthe loading and unloading mechanism '1 Y i 125 i It Will ,.0f course,be'apparent that the operation of initially charging theaccumulatorfwill" I be somewhat lengthened if a pressure lower-thanIOO-p un ds pressure is initially: admitted to the compartmentsS and 6,but that the charging and g l the recharging operations may beaccomplished even though air under pressure is not available. Under suchconditions air at atmospheric pressure is trapped in the compartments 5and- 6 by the,

valve 1'7 is then closed. The further oper'ation'of 5 must bemore'carefully observed.- .That is to 143 say, the water must be raisedto themaximum level in the compartment 5 during each air displacingoperation, since otherwise the operation of charging or recharging willbe greatly lengthened. l

While I have described what I now consider to bathe preferred embodimentof my invention, it will be apparent that omissions, other than thosementioned, and other variations in the apparatus illustrated may be madewithout depart-f are permanently charging or recharging will be asabovedescribed,

ondary compartments of the" accumulator, a

check valve communicating with theupper por- 1 tion-of the primary andwith-the secondary compartment for delivering fluid under pressure ifrom the primaryto the secondary compartment, means for establishingcommunication between said compartments to-deliver fluid from thesecondary to'the primary compartment, means for delivering liquid underpressure to the primary compartment; means for'draining the primarycompartment, and means for connecting the 1 lower-portion of-the primarycompartment to" a liquid distribution system; I 7,

2. A combinedhydro-pneumatic accumulator and "chargingmechanismcomprising a storage chamber for 'compressible fiuids, a compressorchamber, a source of supply of compressible fluid underpressure, branchpipes connecting the source of supplyof fluid with'the storage andcompressor chambers, respectively, a check valve between the supplysource and the branchpipes and a check valve in the branch pipe communhcatingf with the storage chamber permitting flow of-fiuid from thecompressor chamber to the storage-"chamber, a drain for the compressor'chamberpa source of pumped liquid means for alternately connectingthe'bottom of said compressor chambertothe source of pumped liquid andto thedrain, whereby when the compressor "chamber is connected to drain,fluid enters the 'same'to'replace the liquid and when the compressorchamber is connected to the supply of 1 pumped liquid, the fluidiscompressed and de-- livered' to the storage chamber; and retainedtherein by the check valve in the ,branch'pipe connected. thereto,and"means for connecting j the storagechamber with the branch pipeconn'ecting the compressor chamber when the pressure in the storagechamber is of a desired preunder pressure, branch pipes connecting the"source of supply of fluid with thestorage and determined value and thecompressor chamber :is-charged with liquid to a predetermined level.

3'. A combined hydro-pneumatic accumulator .and charging mechanismcomprising a storage chamber forcompressible fluid, a compressorchamber,iasource of supply of compressible fluid compressor chambers,respectively; a check valve between the supply source and the' branchpipes ice 1 ages-m g and acheckvalve in the "branch pipe connecting thesource to f thestorage chamber-permitting the flow of fluid from thecompressor chamber to the storage chamber, a drain" forthe compress'orchamber, asourceof pumped liquid and liquid distribution system, meansadapted to alternately connect the bottom of said compressor chamber tothe source of pumped'liquid and 5 to drain, *whereby when the compressorchamber is connectedto the drain, fluid enters the'same to replac'e'theliquid and whenthe com- 'pressor chamber is connectedto the supply ofpumped liquid, ,thefluid is compressed and deiivered to the storagechamber and retained therein'by the check valve in the'branch pipeconnected thereto, a pipe having avalve therein .forinterconnecting saidchambers in fluid ex- "changingrelation independently of the check valvein said branch pipe when" the pressure in the storage chamber isof adesired predetermined value and the compressor chamberis charged withliquid to a predetermined'level, andmeans i for connecting thecompressor chamber: to'the source of pumpedliquid and to thedistribution system so that both chambers function as an accumulator. I

4; A combined"hydro-pneumatic accumulator Fahd-selfcha r g ingidevicecomprising two independent compartments, a "source 'of supply ofcompressed fluid, branch pipes connecting said compartmentstoth'e-source, a check valve between the source and branch pipes, acheck valve an hydraulic pump and a distribution line there- 'for'means' adapted to alternately "connect the other of" saidcompartrnentsto the drain and to the distribution line, of the hydraulic pump,

initial1yfi1led with compressed fluid at thepressure of the source,"andwhen said last mentioned compartment is connected to the "distributionline'liquid is delivered thereto to compress the I in one ofisaid branchpipes connected to one or" 7 said: compartments permitting .the flow offluid "thereto from the other'compartmentp adrain,

fiuid thereiniiand deliverit :to the other. com

partment wherein the fluid isretained by the connecting saidcompartments in free fluid" exchanging 5 11318111011 when the level oftheliquid predetermined height andthe pressure in the JOSEPH E. HOLVECK;

check valve in said branch pipe, and means for

